Field of the Disclosure
The present disclosure relates generally to optical communication networks and, more particularly, to a credit based approach to calculating optical paths.
Description of the Related Art
Telecommunications systems, cable television systems and data communication networks use optical networks to rapidly convey large amounts of information between remote points. In an optical network, information is conveyed in the form of optical signals through optical fibers. Optical networks may also include various subsystems, such as amplifiers, dispersion compensators, multiplexer/demultiplexer filters, wavelength selective switches, spectral inverters, couplers, etc. configured to perform various operations within the network.
The distance that an optical signal can be transmitted with optical amplifiers for a given data rate depends on the impairments in the transmission system. Typically, the higher the data rate and the denser the wavelength spacing, the more susceptible the transmission system is to impairments. Impairments can include accumulated amplified spontaneous emission (ASE) noise, chromatic dispersion (CD), nonlinear optical effects (such as nonlinear phase noise), polarization mode dispersion, and polarization dependent loss. Digital signal processing (DSP) in coherent optical receivers may compensate for linear impairments such as CD, polarization mode dispersion and polarization dependent loss effectively. Nonlinear phase noise (NLPN) may be mitigated by mid-span spectral inversion when the optical signal is transmitted across multiple spans.
Today wavelength division multiplexing (WDM) optical systems are based on providing the best transmission for each wavelength at each optical network node. In conventional optical networks, optical power may be shared among different optical paths, subject to each path spanning the same distance and having the same modulation type and optical signal-to-noise ratio (OSNR) or bit error rate (BER) limits. In active node systems, such as with reconfigurable optical add-drop multiplexer (ROADM) nodes with active equalization, it may be possible to further optimize transmission so that optical paths can perform in an improved manner.